ensure steps are executed in order

[darwin67]

A potential bug fix.

The executor will send a list of hash, which determines the order of steps ran.
The SDK currently ignore that stack entirely and just uses step/hash mapping, so if the order of a step changed, there might be unintended consequences.

e.g.

this

step "step1" do
  {:ok, %{ hello: "a" }}
end

step "step2" do
  {:ok, %{ hello: "b" }}
end

changed to this:

step "test" do
  {:ok, %{ yo: "lo" }}
end

step "step2" do
  {:ok, %{ hello: "b" }}
end

Resolution

If the code was changed in a way that steps' order are different, the handler should discard the existing memorized data, and redo the execution